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Is there even such a thing, right now I'm useing the hose they sell at HD but I noticed its bigger/thicker than the air line they sell at LFS. Question is which is the best bet to go with an where can I get it from?
 

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They say to use silicone tubing for co2, it's available at nearly every lfs and petsmrtco

Personally, I use whatever tubing I have laying around and Ive yet to run into an issue but its only been 7 months so.

I did get some black silicone tubing from ptsmrt 8ft for 6.99, not bad
 

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Silicone tubing is reported as having a higher leak coefficiency than regular airline tubing (polyvinyl chloride). However, it is still negligible for our purposes, so you can use whatever is cheaper/more available to you.

I had silicone tubing lying around, so that is what I used.

CO2 resistant tubing is not necessary, but if you can obtain it cheaply, then it is fine to use too.
 

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Yea, the notion of CO2 proof tubing always struck me as absurd. I can clearly see the bubbles going into my tank. Whether there is some mystery amount of gas secretly escaping from the sidewalls of the tubing is a non-factor.
 

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Is there even such a thing, right now I'm useing the hose they sell at HD but I noticed its bigger/thicker than the air line they sell at LFS. Question is which is the best bet to go with an where can I get it from?
I use Tygon and clippard co2 tubing. You can get them on e b ay. Type seach word.
 

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Just because we see bubbles going into the reactor or diffuser does not give us 100% of the co2 output. They say to use co2 tubing for a reason. Most of us don't though and we use the tubing we can easily obtain. Silicone tubing membrane allows gas to pass thru its walls unlike true co2 tubing. Now the majority does reach the tank but remember your not getting all from the co2 tank to the aquarium. Also over time silicone tubing gets old and brittle. Connection gets less and less tight and if its not maintained and swapped out, you will be robbed of co2 and wonder if your co2 regulator is faulty and overlook the tubing altogether.
 

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Doesn't this depend on how porous the material is? I would argue that yes we do lose some CO2 to the tubing but is it significant enough to use lab grade equipment? I use Tygon as well and its great but does anyone have firsthand experience with silicone vs tygon?
 

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Already discussed here with numbers.

Sure marketed CO2 resistant tubing is nice but it's sold at a huge premium for marginal gains like the ADA sand flattener ($45!) which can be substituted by a credit card on a stick :icon_roll. I just bought a 20ft roll of vinyl tubing for just a few dollars.
 

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The same topics had been discussed many times.....

here is one of the forum member's rely,
By Snafu, posted 12-31-2005

here's my interpretation of it... what the permeability coefficient tells you, is that net flux (loss) is as follows (from fick's law):
- proportional to the area of the membrane
- proportional to the difference in partial pressures inside and outside of the membrane
- inversely proportional to the thickness of the membrane

or net flux = permeability constant x area x deltaP / thickness

essentially... for a given tubing thickness, ID, length of tube, and operating pressures, the silicone will lose about 20132/90 times more CO2 than polypropylene (224x) tubing.

Example calculation:
1) area = PI x diameter x length of tubing
= PI x 0.47625cm x 30.28cm
= 45.60 cm2

if we assumed the following
ID = 3/16 inch = 0.47625 cm
length = 1 foot = 30.48 cm

2) deltaP = pCO2_inside - pCO2_outside
= 77.572 mm-Hg - 2.386 mm-Hg

if we assumed the following
0.0314 = CO2 mole percent in dry air
76 cm-Hg for std atmospheric pressure
pCO2_outide (Dalton's law) = 76 cm-Hg x 0.0314

pCO2_inside = 15 psi = 77.572 cm-Hg (pure CO2)

3) thickness = 1/32 inch = 0.79375 mm

4) permeability constant for silicone = 20132e-10 cc-mm/(sec-cm2-cmHg)

Therefore,

net flux_silicone = 20132e-10 x 45.60cm2 x 75.2cm-Hg / 0.79375mm
= 0.0087 cc/sec (Loss)

Assuming you are bubbling at 2 bubbles per second:
Let each bubble be around 0.5cm in diameter (SWAG)
volume (sphere) = 4/3 PI R^3
= 0.065 cc

Bubble_rate = 2 bubbles per sec x 0.065 cc
= 0.13 cc/sec

Net CO2 loss would be around 0.0087 / 0.13 = 6.6% per ft of tubing. so, a short run of silicone tubing (i.e., several feet could mean a non-trival amount of CO2 loss).

-snafu
http://www.plantedtank.net/forums/showpost.php?p=213172&postcount=11
 

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Already discussed here with numbers.

Sure marketed CO2 resistant tubing is nice but it's sold at a huge premium for marginal gains like the ADA sand flattener ($45!) which can be substituted by a credit card on a stick :icon_roll. I just bought a 20ft roll of vinyl tubing for just a few dollars.
regular vinyl air hose is ok, the co2 permeability is really low, but after one or two years, it will harden, bristle due to UV damage especially for the planted tank.

try lab grade polyvinyl, better than regular vinyl.
 

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Its not so much the permeability of the hose the hose in question but for me its hardening over time and the hoses ability to stay on whatever you're using to attach the hose to your set up. In short, the higher quality stuff generally works better in higher pressure situations.
 
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